Smart Lock currently leaves the BLE connection to the phone open indefinitely (unless the laptop lip is shut). This is risky; if the connection breaks, it could leave the phone's or Chromebook's BLE or Weave stack in a weird state.

There are 2 things we should change here:
1) When the screen turns off, disconnect the BLE connection. Retry the BLE connection once the screen turns back on. This will behave very similarly to current laptop lid closing and opening.
2) After a minute, if the screen is still on, disconnect the BLE connection. There's no signal I know of, e.g., screen turning back on, that can tell us to retry the connection in the future, so this won't be recoverable; the user will need to enter their password. This will likely require a new UX that explains to the user something like "canceled Smart Lock unlock while waiting for user input, please enter password". This sounds pretty clunky and awkward, so Shiba and Jesse, let me know if you disagree with this, can think of better language, or see a better approach to this problem.